Tuesday December 17 2013
Taller people had a lower risk of a marker of CHD
"Tall people are less likely to have a heart attack because their arteries aren't so clogged," reports the Mail Online. But the Mail's claim that "taller people have a towering advantage when it comes to heart disease" isn't necessarily true.
The news was actually based on research that found an association between an adult's height and the odds of having calcium in the arteries that supply the heart. This coronary artery calcium is a sign of atherosclerosis (clogging of the arteries), a known risk factor for coronary heart disease (CHD), which can lead to heart attacks.
The researchers did indeed find that taller people had reduced odds of having coronary artery calcium, as the Mail reported. The tallest 25% of men and women had a 30% reduced chance of developing coronary artery calcium compared with the shortest 25%.
Previous studies have shown a link between coronary artery calcium and the risk of CHD events such as a heart attack. But this study didn't directly investigate whether taller people had a reduced risk of CHD events. In fact, none of the people in this study had established CHD.
Although it's plausible that the differences in levels of coronary artery calcium according to height could be associated with differences in the risk of CHD or heart attack, this isn't proven by this study. Further research is required to see whether tall people actually have fewer heart attacks.
Where did the story come from?
The study was carried out by researchers from Harvard Medical School, Minneapolis Heart Institute, Minneapolis Heart Institute Foundation and other American universities. It was funded by the US National Heart, Lung, and Blood Institute.
The study was published in the peer-reviewed journal Circulation: Cardiovascular Imaging.
Although the majority of Mail Online's reporting of the study was good, the article interpreted the results as meaning that tall people are less likely to have a heart attack. The study actually found that tall people are less likely to have coronary artery calcium.
Although previous studies have shown a link between coronary artery calcium and risk of CHD events such as heart attacks, this study didn't directly investigate whether taller people were at a reduced risk of CHD events. Further research is required to see whether tall people actually have different health outcomes.
What kind of research was this?
This was a cross-sectional study. Its aim was to find out whether there was a connection between height and coronary artery calcium. Coronary artery calcium is a marker of atherosclerosis, where arteries become clogged because of a fatty build-up of cholesterol and other materials such as calcium.
Atherosclerosis, also known as CHD, can lead to a heart attack if one or more of the areas of fatty build-up ("plaques") rupture and form a blood clot that completely blocks the artery.
Cross-sectional studies are a good way of determining how many people have coronary artery calcium, but they can't tell us whether this factor directly relates to disease events such as heart attacks later in life.
What did the research involve?
The researchers collected information on height and the presence of coronary artery calcium in 2,703 people participating in the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study.
The study aims to evaluate genetic and non-genetic predictors of CHD. Some participants were selected randomly, while other participants were selected because they had risk factors for cardiovascular disease.
Coronary artery calcium was examined using CT scans. The researchers examined the heart from a number of angles and looked for the presence of plaques, which are made up of immune cells, cholesterol and calcium.
The researchers calculated odds ratios for the presence of coronary artery calcium depending on height in men and in women.
They adjusted for standard cardiovascular risk factors, including:
- waist circumference
- alcohol intake
- physical activity
- systolic blood pressure
- antihypertensive (blood pressure) medications
- diabetes and diabetic medications
- low-density lipoprotein (LDL, "bad") cholesterol and high-density lipoprotein (HDL, "good") cholesterol
- lipid-lowering (fat-lowering) medications, such as statins
What were the basic results?
The study found that:
- the tallest 25% of people had 30% lower odds of having coronary artery calcium than the shortest 25% of people (odds ratio [OR] 0.70, 95% confidence interval [CI] 0.53 to 0.93)
- for each standard deviation increase in height, the odds of having coronary artery calcium fell by 14% (OR 0.86, 95% CI 0.74 to 1.00)
How did the researchers interpret the results?
The researchers concluded that they found "a significant inverse relationship between adult height and prevalent coronary artery calcium. Individuals in the tallest quartile had 30% lower odds of prevalent coronary artery calcium compared to individuals in the shortest quartile.
"Whilst the prevalence of coronary artery calcium differs amongst men and women, the inverse association between height and coronary artery calcium was similar in both genders."
This study has found an association between an adult's height and the amount of coronary artery calcium they had. Coronary artery calcium is where the arteries become clogged as a result of a fatty build-up of cholesterol and other materials, such as calcium.
After adjusting for standard cardiovascular risk factors, the study found that taller people had reduced odds of having coronary artery calcium. The tallest 25% of men and women had 30% reduced odds of coronary artery calcium compared with the shortest 25%.
This study has a number of strengths and limitations that should be considered when interpreting the results.
The study included information on a large number of people, collected information on standard cardiovascular risk factors, and used a standardised approach to coronary artery calcium assessment.
However, there were a number of limitations, including:
- height was self-reported
- there may be other factors that were not adjusted for that could explain the link between height and coronary artery calcium – for example, although the researchers adjusted for waist circumference, they haven't assessed body mass index as another indicator of being overweight or obese
- information on childhood factors that could influence height was not available
- the study was performed in America and participants were mainly white – the association between height and coronary artery calcium may not be the same for all populations
The biggest limitation was that coronary artery calcium is a surrogate marker (possible indicator) of CHD and CHD events such as heart attack. Although previous studies have shown a link between coronary artery calcium and the risk of CHD events, this study didn't directly investigate whether taller people had a reduced risk of these events.
Further research is required to see whether tall people actually have different health outcomes. For now, while we can do nothing about our height, we can lower our risk of developing CHD by eating a healthy balanced diet, taking regular exercise and not smoking.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.